Patent application CN102810145A has disclosed a method and apparatus for card reading through mobile terminal within safety distance determined by ultrasonic wave. According to the method and apparatus, the distance between a mobile terminal and a card reading device is measured according to the propagation time of the ultrasonic wave in the air, which prevents the measurement from cheating and attacks. However, the method still has the following defects:
Firstly, although the card swiping distance can be ensured within a predefined secure distance, an attacker may perform card swiping within the predefined secure distance with no need of making the card reading device in close contact with the mobile terminal, thereby acquiring money and other information from the mobile terminal. Since the money is in a very small amount, the owner of the mobile terminal may fail to detect such loss. Even if the owner detects the loss, the owner still finds it very difficult to find any evidence or find it unworthy to spend time to find any evidence for getting back the loss.
Secondly, the ultrasonic sensor is configured on the multi-interface integrated circuit card in the mobile terminal. Since the shell of the mobile terminal exerts a resistant effect to the ultrasonic wave, the ultrasonic signals reaching the ultrasonic sensor are subjected to great attenuation. A majority of mobile terminals fail to receive sufficiently strong ultrasonic signals, or may receive the signals only when the ultrasonic wave strength is enhanced to a great value. This increases the cost and power consumption of the card reading device, and limits the application scope of the card reading device. In this way, the adaptability of the multi-interface integrated circuit card is restricted, and thus card swiping within a secure distance fail to be implemented by using the ultrasonic wave in most mobile terminals.